This is very much untrue. I manage several open source projects and contributors save me tons of time. You have to mold contributors into the productive team members you need them to be to save you time. I often receive pull requests from first time contributors that are not immediately mergable. I don't take the approach of just merging it and fixing it myself - I do invest the time in coaching the contributor into making their pull request a strong candidate for merge on their own. This often produces returning contributors who get it right more and more often on the first try and can be trusted to write larger and more important swaths of the code. Bonus - these contributors you've worked with will often start to get in and help review entry-level pull requests, too, which reduces your workload even more for onboarding new contributors.
Contributors rock! More of them would help me get my projects done so much faster.
I do the same, but I wish more contributors who just want to dump a patch would say so from the get go. Otherwise, you start debating why a certain change needs to be made, and only after a couple days they say "please, take it or leave it". It's not wrong to just dump a patch, but include it in the description, and if the change is useful, I will rework the patch to fit. Thankfully, such contributors have been rare in the projects I'm involved in.
My hunch is that there are several factors that make outside contributions easier to leverage or less so.
One of course is the maintainer's ability to mentor new contributors into becoming co-maintainers - writing guides etc.
Another would be a project's scope. If it's really small, then people will step on each other's toes.
Yet another would be "fun-ness" - how intrinsically rewarding it is to work on the project. It would be alot harder to get people to stick around if they find the work tedious.
"I make unoriginal projects with better code than the thing they rip off."
Love that line. That's what we high-assurance people keep telling developers to do to all the established stuff. You said it better, though. Might remix that in some way with your permission. :)
Contributors rock! More of them would help me get my projects done so much faster.